Microfluidics is the science behind the manipulation of continuous or discrete volumes of liquid on the microlitre scale. Devices using microfluidics offer high-throughput, low cost versions of traditional analytical techniques and have found use in a variety of fields including combinatorial chemistry and drug screening. They have particularly found use in the field of biochemical assays where low analyte concentrations become a concern.
Microfluidic devices generally comprise an inlet region and a detection zone wherein the inlet region and the detection zone are connected by one or more channels and wherein the detection zone is downstream from the inlet region. A fluid sample to be analysed is placed in the inlet region and then progresses through the device to the detection zone where the presence of an analyte of interest can be assessed. In order to provide an accurate working of the device, it is important to control the flow of the fluid sample from the inlet region to the detection zone. For example, it is often necessary to retain the sample in a particular region to allow an adequate incubation time.
Previous methods for controlling the flow of a fluid in a microfluidic device have included the use of fluid gates which are responsive to changes in pH. However, such methods may not be widely applicable since the pH of the fluid sample may have to change in order for the fluid gate to be opened. It would be beneficial if there existed a mechanism by which the flow of the fluid could be controlled wherein such mechanism did not depend upon effecting changes to the chemical characteristics of the fluid.